Exactly that vanishing of the linguistical heritage we are seeing in Serbia today as well as from the time of Vuk Stef. Karadzic, where almost every Serbian word considered archaic (or out of use) is being replaced with a more efficient, or sometimes just 'cooler' foreign one. I am strongly opposed to that, but stand in a grave minority.
The Serbian language will vanish with time, thanks to uneducated masses. One would have to go to Zagreb to learn Serbian, just as it was predicted 150 years ago.
This is absolutley wrong standpont.
1) Hochdeutsch is based on Saxonian dialect. From XV century it is language of German literature, but nontheless it is based onvernaculare in Meisen. On other hand, before Vuk Stefanović Karadžić, literary language of Serbs was not Serbian, but Old Church Slavonic and Chruch Slavonic later. This is akin to medieval Europe, literary language was Latin, not Spanish French, German. Slavjanoserpski is just suržik, not language on its own, mixture of vernaculare Serbian, Church Slavonic and Russian
Весьма бы мені пріскорбно было, ако бі я кадгод чуо, что ты, мой сыне, упао у пянство, роскошь, безчініе, і непотребное жітіе.
Nevertheless, tradition of use vernacular in literature did not start with Vuk Stefanović Karadžić, century and half before him Gavril Stefanović Venclović wrote about 10 000 pages in vernaculare.
2) Russian words and Croatian neologisms (not intented as offense, it is ligusitc term) are not archaic Serbian words. Sometimes it is more efficient ot accept foreign word, фудбал is both game and ball for that game. Интернацинални could be used for deriving more words than међународни.
3) If somebody go in Zagreb in order to learn proper Serbian, he is absolutley wrong. In Zagreb they could not diferentiate č and ć, they do not differ ije and je (being ekavians), ther isn no 4 accents, but 3, there is one phonema more. If somebody wants to speak Serbian properly, he should go in Universities of Belgrade and Banja Luka (dont know about other Universities), majority of professors on that two speak proper Serbian.
Maybe someone went in school in Croatia or something. Serbs in Drvar speak сто and soko. Their dialect is same as mine (East Herzegvonian)